Microwave cooking often offers advantages of speed and convenience in heating foods. However, the heating characteristics in a microwave oven for some food products is dramatically different from that experienced in a conventional oven. One problem with microwave cooking is that necessary temperatures for browning and crisping of the surface of food products typically are not achieved. Moreover, microwave cooking may leave the food surface soggy, which is oftentimes undesirable and detrimental to the texture and taste of the food. These are old problems in the art, and many attempts have been made to solve them.
In the past, attempts to solve some problems with microwave cooking have involved the use of susceptors which heat in response to microwave radiation. Typically, susceptors have been used which contain a thin film of aluminum deposited upon a polyester film substrate which is in turn bonded to paper. U.S. Pat. No. 4,641,005 discloses a thin film susceptor of this type. Typically, such thin film susceptors will deteriorate or break up during microwave heating. This deterioration and breakup of the susceptor can significantly change its performance characteristics, and for many food products, this is undesirable. Also, undesirable nonuniform heating effects across the surface area of the food product may result. Undesirable nonuniform heating as a function of time for a given area of the susceptor during the period of time that heating occurs may also result. For example, attempts to heat large pizzas with a thin film susceptor have generally resulted in overheating of the outside of the pizza, and underheating of the center of the pizza. The outside edge of the crust could be burned, while the center area came out soggy.
One solution to problems associated with microwave cooking is disclosed in Applicants' U.S. Pat. No. 4,927,991. A susceptor may be used in combination with a grid to achieve more uniform heating. The present invention provides an alternative to the use of a susceptor in combination with a grid for certain applications.